What You Should and Shouldn’t Eat Before a Run

Whetheryou’re a neighborhood jogger or an ultramarathoner, fueling right will help you get the most out of every mile. Eating well before you run can prevent sudden fatigue mid-workout (aka hypoglycemia, or bonking) and can have a direct impact on your performance. “What you eat will help you through the run by either building your glycogen stores for a workout later or boosting blood sugar for a workout in the short term,” says nutritionist Amy Shapiro, founder of Real Nutrition NYC. As you start to increase your mileage, your body requires extra fuel—and eating right gets even more important.

Foods to Avoid Before a Run

Foods high in fat, fiber, and protein are best avoided right before you hit the pavement or trail. “Too much fat or protein before a run can cause cramping or tiredness, as your body will be spending energy on digestion instead of running,” Shapiro explains. High-fiber foods can also lead to GI distress and cramping because they are hard to fully digest, so they move through your system rapidly. Some runners swear by a caffeine boost, but be careful not to overdo it on coffee or tea for all the same reasons you wouldn’t want to overdo it at the office—elevated heart rate, stomachaches, and frequent bathroom trips. These foods could be rough for digestion before a run:

Legumes

Broccoli, artichokes, or other high-fiber veggies

Apples, pears, or other high-fiber fruits

Cheese, red meat, bacon, or other high-fiber foods

Caffeine (in large amounts)

Spicy foods

Foods to Eat Before a Run

The ideal pre-run snack is easy to digest and provides instant fuel, Shapiro says. Foods higher in carbohydrate content are best, because carbs break down into glucose, the body’s main source of energy during a run. Glucose circulates in the bloodstream, where it can be used for immediate energy, or it gets stored as readily accessible glycogen in the muscles and liver. A little bit of protein and fat can provide some staying power, but the majority of your pre-run fuel should be carbs. Shapiro encourages opting for real foods when possible, rather than sticking to bars and energy gels. Her go-to snacks:

Banana and almond butter

Turkey and cheese on whole-wheat bread

Oatmeal and berries

Cheese stick and carrots

Toast with 1/4 avocado or one to two tablespoons of nut butter

When to Eat

The ideal pre-run meal is generally 300 to 400 calories, consumed around two hours before you hit the road, Shapiro says. Even if you’re going long, you’re better off fueling mid-run than loading up too much beforehand. If you’ve eaten a larger meal, you may need to wait up to four hours before running to prevent stomach discomfort, although 30 minutes is usually enough after a light snack, she says.

Exactly how much you ought to consume varies slightly based on your body and your workout, of course. For an easy run of less than an hour, aim for 15 grams of carbs. “Most people can get through a three-mile run without food beforehand,” Shapiro says. “But it might be easier to get through the three miles if you have a small carbohydrate snack, such as a piece of fruit.” If you’re doing a longer or more intense workout, go for 30 grams of carbs. Before a marathon, you’re looking at something between 50 and 75 grams. For runs longer than 75 minutes, you’ll also need to think about bringing along some mid-run fuel, because your glycogen stores will be depleted. Shapiro advises 30 to 60 grams of carbs for every additional hour you’ll be out, as well as added electrolytes and extra fluids.